The present invention is directed to substantial elimination of unreacted ammonia and the dramatic reduction in ammonium sulfate and resulting waste products produced from the unreacted ammonia during the manufacture of acrylonitrile by the direct ammoxidation of an unsaturated or saturated hydrocarbon, preferably propylene or propane, ammonia and oxygen in a fluid bed reactor containing an ammoxidation catalyst. In particular, the present invention is directed to the addition of oxygen containing compound, preferably methanol, at a specific location in the fluidized bed reactor during the manufacture of acrylonitrile to reduce substantially or eliminate the amount of ammonia remaining in the gaseous effluents exiting the fluidized bed reactor which translates into a complete or substantial reduction of the production of ammonium sulfate during the recovery and purification of the acrylonitrile so produced. This substantial reduction or complete elimination in the generation of ammonium sulfate during the practice of the manufacture of acrylonitrile leads to significant environmental and economic advantages.
There are several patents which address the issue of the injection of methanol into a fluid bed reactor to produce hydrogen cyanide. In addition, these references further disclose the injection of methanol into an acrylonitrile fluid bed reactor to produce hydrogen cyanide while manufacturing acrylonitrile. For example, U.S. Pat. Nos. 3,911,089 and 4,485,079 each teach the ammoxidation of methanol to produce hydrogen cyanide by injection of methanol into a fluid bed reactor containing an ammoxidation catalyst suitable for the manufacture of acrylonitrile. In addition, each of these references teach that the methanol injection can be made simultaneously with the manufacture of acrylonitrile. Moreover, Japanese Patent Applications 74-87,474, 79-08655 and 78-35232 all are related to similar methods of increasing or making hydrogen cyanide during the manufacture of acrylonitrile. Japanese patent application 74-87,874 also suggests that a secondary effect of their procedure is the decrease of the amount of unreacted ammonia with a resulting decrease in the amount of sulfuric acid used for neutralization. All of these patents are primarily concerned with the production of additional hydrogen cyanide.
The present invention is directed to a specific procedure for injection of an oxygenate compound(s) or mixture or organic materials capable of reacting with ammonia, preferably methanol, into the fluid bed reactor at a specific location and direction to obtain substantial or complete elimination of the production of ammonium sulfate produced during the manufacture, recovery and purification of the acrylonitrile without any decrease in the acrylonitrile production.